Indicating teeth cleaning time

ABSTRACT

The invention relates to an electric tooth cleaning device and to a method for automatically indicating the cleaning duration when cleaning teeth, whereby a timer signal is emitted using a time element after the termination of a set cleaning duration in a tooth cleaning session. According to the invention, the set cleaning duration, whose termination prompts the emission of a timer signal, is modified. An actual cleaning duration in the tooth cleaning session is registered by a time registration device. The deviation of the actual cleaning duration from a predetermined standard cleaning duration is determined by means of an evaluation device. The set cleaning duration of a subsequent tooth cleaning session is then defined depending on the deviation that has been determined.

TECHNICAL FIELD

The present invention relates to a method for indicating the cleaning time in teeth cleaning.

BACKGROUND

It is known with electric tooth brushes to provide a time switch, which, starting from switching-on of the electric tooth brush, emits a discernible signal after a predetermined time duration for a user. The signals serve to indicate to the user the end of the cleaning time. The user is made aware of the end of the optimal cleaning time through the use of acoustic or optical signals. From WO 96/14025, it is known to not emit an acoustic or optical timer signal, rather instead to switch the drive motor of the tooth brush on and off rapidly so that the drive motor stutters. This can be done while the device is either in the hand or in the mouth of the user.

In addition, it can be provided that the electric tooth brush is switched off after termination of the target cleaning time automatically. This is inexpedient if the timer-signal merely indicates that a partial region of the teeth, such as, for example, a biting quadrant, has been completely cleaned. In WO 97/19650, it therefore proposed to switch again to regular cleaning operation after the stuttered operation, so that the biting quadrant can be cleaned completely according to the desire of the user. As soon as the user changes to another biting quadrant, he can start anew the timing member by means of a button, in order again to be provided the target cleaning time for this new biting quadrant. This method for indicating the target cleaning time does not fulfill the wishes of all tooth brush users, however.

From DE 197 28 964 A1, a tooth brush with a device is known, which signals to the tooth brush user the beginning and end of the optimal tooth cleaning time. On the tooth brush, a knob or slide switch is mounted, with which at the beginning of the teeth cleaning, an acoustic signal can be released, which is repeated automatically after approximately three minutes. In addition, a signal after approximately three months of using the tooth brush can be emitted, whereby the user is informed that the tooth brush should be replaced with a new tooth brush.

U.S. Pat. No. 6,029,303 discloses a manual tooth brush with an electric circuit, which emits a discernible signal regarding the cleaning time. The beginning of the cleaning time can be determined, for example, by means of a movement sensor, which releases a timing member, whereby, at the end of the time, a signal discernible by the user is emitted from the timing member of an electrical circuit. Also, the possibility exists that with the electronic circuit, the entire cleaning time is added up and a further signal from the electronic circuit is then emitted, which falls below the recommended use time of the tooth brush.

SUMMARY

The present invention is based on the object of producing an improved tooth cleaning device as well as an improved method of the above-disclosed type. Along with deviation of the actual cleaning time from the predetermined target cleaning time in an individual case, a mean value for the actual cleaning time can be reached over multiple, separately successive cleaning processes.

The target cleaning time is variably determined, particularly, when predetermined cleaning times are not obtained from the user. An actual cleaning time of the tooth cleaning process is determined by means of a time determination device. By means of an evaluation device, the deviation of the determined actual cleaning time from a predetermined constant or variable standard cleaning time, depending on parameters, is determined. A control device determines the target time for a subsequent tooth cleaning process. This determination depends on the deviation determined by the evaluation device. After termination of the target time, a timer signal is emitted.

The target cleaning time can be adapted personally to the cleaning environment and/or for example, to the daily rhythm of the user. Behind the variable timer-signal, the consideration exists that a combination of short and longer cleaning processes resulting from the variable timer-signal can lead to a good or satisfactory cleaning result, because a cleaning process that was too short is compensated by a lengthened cleaning time in a subsequent cleaning process. The variable standard cleaning time can adopt different values that are user-specific. For example, the variable standard cleaning time may differ between children and adults. It may also be cleaning-tool specific. For example, the variable standard cleaning time may differ depending on the type of implement used, such as a flat brush, inter-dental brush, floss offset or the like.

In a further embodiment of the invention, a cleaning time account is managed, which takes into consideration the deviations of the actual cleaning time from the predetermined standard cleaning time with multiple, previous tooth cleaning processes. Thus, the sum of deviations over multiple tooth cleaning processes is determined. A cleaning time memory can be provided, which stores the sum of deviations between the actual cleaning time and the standard cleaning time determined from multiple tooth cleaning processes. The control device uses the cleaning time memory with the determination of the target cleaning time for a new tooth cleaning process and determines the target cleaning time based on the determined deviations from one or more previous cleaning processes. With multiple deviations, correspondingly marked changes of the target cleaning time take place. In particular, the target cleaning time relative to the standard cleaning time is markedly lengthened when only one shortened tooth cleaning process was performed. Similarly, the target cleaning time relative to the standard cleaning time may be markedly shortened when only one lengthened tooth cleaning was performed.

Preferably, the deviations between actual cleaning time and standard cleaning time only up to a predetermined amount are taken into consideration. In particular, the deviations between the actual cleaning times and the standard cleaning times can be added up only to a known capping limit and can be stored in the cleaning time memory. Upon exceeding the capping limit, the threshold value can be taken into consideration or the target time change can be considered.

It is likewise possible not only to limit the sum of the deviations, but also to provide a capping limit for the individual deviations. If the actual cleaning time deviates too intensely from the predetermined standard cleaning time, only the provided maximum amount of the deviation is considered for the change of the target cleaning time of the next tooth cleaning process. Such a limitation of the considered deviations is based on the conclusion that a known frame and optimal tooth cleanliness cannot be achieved when the fluctuations are too marked. Thus, only deviations within a predetermined range change the target cleaning time.

In particular, it can be provided that the control device determines the target cleaning time always within a predetermined range. This range basically can be formed differently. Thus, in particular, a maximum lengthening of the target cleaning time can be provided.

The range limit for the target cleaning time can be determined differently. According to an advantageous form of the invention, the standard cleaning time can be provided as the minimal target cleaning time. The control device determines the target cleaning time always as greater or the same as the standard cleaning time. When the user positively fills up his cleaning time ledger by too long of a tooth cleaning over the target cleaning time, the timer is not activated before the standard cleaning time by the control device during the next tooth cleaning process.

According to an alternative embodiment of the invention, it can be provided that the target cleaning time can not only be lengthened, but also shortened relative to the standard cleaning time. For the cleaning time account, then, cleaning times over the target cleaning time are also taken into consideration and referenced for the determination of the next target cleaning time. If the user, for example, cleans his teeth in the evening for a particularly long time over the standard cleaning time, a corresponding credit is placed on the cleaning time account and the target cleaning time on the next morning is correspondingly shortened.

The deviations determined with a previous cleaning process or with multiple previous cleaning processes can be taken into consideration in various ways with the determination of the target cleaning time. Thus, it can be provided that the deviations are passed along only in part with the change of the target cleaning time. For example, a cleaning time that lasts 30 seconds over the standard cleaning time can lead to only a 15-second shortening of the next target cleaning time. According to an advantageous embodiment of the invention, the determined deviation or the sum of the determined deviations between actual cleaning times and standard cleaning times is directly abstracted. Thus, a one-to-one determination of the target time to the standard cleaning time is proposed or abstracted. This takes place preferably only within the determined limits, so that the target cleaning time is changed only within the predetermined capping limits.

In a further embodiment of the invention, only tooth cleaning processes that last longer than a minimum time are taken into consideration for the cleaning time account. If the actual cleaning time of a tooth cleaning process lies below the minimum limit, which are determined by different, for example, user- or cleaning-tool-specific factors, no deviation between the actual cleaning time and the standard cleaning time is determined or this is not taken into consideration with the determination of the target cleaning time of a later tooth cleaning process. The minimum time is preferably 30 seconds.

In order to better signal to the user of the tooth cleaning device the adaptation of the time or his deviation from the standard cleaning time, a corresponding warning signal is emitted, which indicates to the user that the last tooth cleaning process was too short and a correspondingly longer target cleaning time is necessary for the current tooth cleaning process. The warning signal is preferably emitted at the beginning of the respective tooth cleaning process.

In a further embodiment of the present invention, it can be provided that upon termination of a tooth cleaning process before reaching the standard cleaning time, a warning signal is emitted, which indicates to the user that he cleaned his teeth for too short of a time. A further warning signal is preferably provided when the tooth cleaning process is interrupted before reaching the respectively variable target cleaning time. Accordingly, the noted warning signals are different from one another, so that it is clear which change or deviation is made or occurred.

In order to achieve a measured determination and evaluation of the actual cleaning times, a coast down timer can be provided. With the determination of the actual cleaning time, temporary interruptions of the tooth cleaning process can be ignored. This can be particularly sensible with a temporary on/off switching of the tooth cleaning device. This may occur, for example, upon changing from one biting quadrant to the next biting quadrant or when tooth paste is removed from the mouth and the tooth brush is turned off temporarily. If the time determination and the corresponding evaluation were run anew each time, few sensible results would be achieved.

Next, the invention will be described in more detail with reference to a preferred embodiment and associated drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic representation of an electric tooth brush according to the present invention;

FIG. 2 is a block diagram of a variable timing member of the electric tooth brush according to FIG. 1; and

FIG. 3 is a flow diagram of the variable timing member, which makes clear the changes of a cleaning time account over multiple cleaning processes.

DETAILED DESCRIPTION

In FIG. 1, an electric tooth brush 1 is shown, in which a housing 2, an accumulator 3, a motor 4, and a drive 5 are accommodated. On a free end of the electric tooth brush 1, an attachment brush 6 can be inserted, which has a rotary-supported stiff-bristled support 7 with bristles 8 attached thereto. The bristle-support 7 can be rotary driven in an oscillating manner about a rotational axis that is essentially perpendicular to the longitudinal axis of the attachment brush 6 in a known manner by the motor 4.

In the housing 2 of the tooth brush 1, a coil 9 as well as a control device 10 in the form of a circuit board are accommodated. The coil 9 is arranged on the end of the housing 2 lying opposite the attachment brush 6 and serves for charging the accumulator 3. The control device 10 includes various electronic components, which control the operation of the electric tooth brush 1. Accessible from outside, a switch 11 is arranged in the wall of the housing 2, with which the motor 4 of the tooth brush can be switched on and off. An output unit 12 is arranged in the wall of the housing 2, which is connected with the control unit 10 and serves to emit signals, in particular, a timer signal, for indicating the termination of the target cleaning time. The signals emitted by the output unit 12 can be variously formed, for example, optically or acoustically. Also, other output of the signals can be provided. For example, the motor 11 can be placed into a stuttering operation, such as described in WO 97/19650. Regarding the structure of the timer-signal in this connection, specific reference is made to WO 97/19650.

The control device 10 includes, in particular, a timing member or a timer for production of a timer-signal after termination of a target cleaning time. Such a timer is shown in FIG. 2 and is generally designated with reference numeral 13. In a memory 14, first cleaning constants are stored, which dictate the boundary conditions of the target cleaning process. In particular, a standard cleaning time and a minimum cleaning time for an effectual cleaning process can be stored in the memory.

In addition, a time determination device 15 is provided, which can be activated by a switch 11 for switching on the motor 4. Preferably, it includes a coasting down means, so that with temporary interruptions of the motor operation, it continues to run. It determines the time between switching on of the motor 4 and its definite switching off.

A central component of the timer or the timing member for emitting the timer signal is the evaluation device 16, which has access to the memory 14 and which is connected with the time determination device 15 in order to obtain the actual cleaning time. It determines the deviation of the respectively determined actual cleaning times from the standard cleaning times stored in the memory 14. It places the determined deviations on a cleaning time account MPK, and determines with reference to the deviations from previous tooth cleaning process the target cleaning time, after whose termination a timer-signal is emitted. The memory 14 and the cleaning time account MPK can be formed from separate storage components, as shown in the drawing. Alternatively, however, they can also be formed as a common memory.

For outputting the timer signal, the evaluation device 16 is connected with the output unit 12. The output unit 12 can emit a timer-signal 17, which indicates the termination of the variably determined target cleaning time. In addition, the output unit 12 can emit different warning signals 18, which indicate to the user different deviations or changes of the time switch. In particular, a sub-minimum warning signal W1 can be emitted, when a cleaning process is discontinued under the minimum cleaning time. A sub-target warning signal W2 can be emitted, when the user switches off the apparatus before reaching the timer-signal 17. The sub-target warning signal W2 preferably can be distinguished from the first warning signal W1. Finally, in order to note a changed target cleaning time, relative to the standard cleaning time, with the next cleaning process, a non-standard warning signal W3 or advisory signal can be emitted, which is distinguishable from the previous signals and indicates to the user that the timer-time was changed. The named signals can be emitted optically or acoustically. Also, the previously described stuttered-motor can be provided. Other signal output forms are possible.

Next, the function of the tooth brush 1 and in particular, the timing member 13, will be explained in greater detail with reference to different cleaning processes in connection with FIG. 3.

First, the cleaning time account MPK guided by the evaluation device 16 is empty. For the cleaning time account, a capping limit of 90 seconds is provided, that is, deviations between actual cleaning time and standard cleaning time up to merely a total of 90 seconds can be added up. The cleaning time account has a capacity of 90 seconds. The standard cleaning time stored in the memory 14 amounts to 120 seconds in the shown embodiment. The minimum cleaning time likewise stored in the memory 14 for an effectual cleaning process is determined with 30 seconds.

With a first cleaning process, the user terminates his cleaning process after 15 seconds, without waiting for a signal from the timing member 13. The sub-minimum warning signal W1 indicates that the cleaning process was too short and is not valued for the time balance. Accordingly, the cleaning time account remains empty.

With a second cleaning process, the user terminates his cleaning process after 105 seconds, again without emission of the timer-signal. The warning signal W2 indicates that the recommended standard cleaning time has not been reached. The evaluation device 16 determines the deviation between the actual cleaning time and the stored standard cleaning time. The difference of 105 seconds and 120 seconds, namely, 15 seconds less time, is added to the cleaning time account. The cleaning time account obtains therewith the value of 15 seconds less time.

With a third cleaning process, the timer is reconfigured. The target cleaning time is placed to a value differing from the standard cleaning time. The target cleaning time is set up to the sum of the standard time of 120 seconds and the stored value of 15 seconds, namely, to 135 seconds. In order to make noticeable the now-lengthened cleaning time, this non-standard warning signal W3 sounds directly after the switching on of the tooth brush, in order to indicate to the user that a lengthened target cleaning time is to be obtained. The user, however, terminates his cleaning after 90 seconds without the timer-signal. The sub-target warning signal W2 sounds. The evaluation device 16 determines anew a less time of 30 seconds. This deviation is added to the previously determined deviation, so that the cleaning account is set at a value of 45 seconds.

With a fourth cleaning process, first the timer is adjusted corresponding to the deviations stored in the cleaning time account. On the standard cleaning time of 120 seconds, the sum of the deviations of 45 seconds stored in the cleaning time account is added, so that the target cleaning time is adjusted to 165 seconds. With switching on, the warning signal W3 sounds, which provides the lengthened target cleaning time. The user terminates his cleaning process this time after 135 seconds without the timer-signals. The warning signal W2 sounds anew. This time, however, the value of the cleaning time account is reduced, since the cleaning process lasted longer than the standard cleaning time of 120 seconds. The less-cleaning time is reduced by the difference of 135 seconds to the standard cleaning time of 120 seconds. In the cleaning time account, a less time of now 30 seconds is stored.

With a fifth cleaning process, the target cleaning time corresponding to the less time of 30 seconds is set to 150 seconds, which corresponds to the sum of the standard cleaning time and the stored less cleaning time. Upon switching on, signal W3 sounds anew. The user terminates his cleaning process, however, after 45 seconds without the timer-signal, so that the sub-target warning signal W2 sounds anew. The evaluation device 16 determines a deviation of 75 seconds to the standard cleaning time of 120 seconds. Accordingly, the cleaning time account must be set to a less time of 105 seconds. Since, however, a capping limit of 90 seconds for the cleaning time account is provided, the threshold value of the less time of 90 seconds is stored in the cleaning time account.

According to the maximum less time of 90 seconds, which is stored in the cleaning time account MPK, the target cleaning time and, accordingly, the timer 13 is set to the sum of the standard cleaning time of 120 seconds and the maximum less cleaning time of 90 seconds, that is, to 210 seconds. Upon switching on the tooth brush, the warning signal W3 sounds anew. The user cleans for the set timer time and after 210 seconds, the timer signal 17 is emitted from the output unit 12. Since the target cleaning time would be completely processed, the cleaning time account is reset. The stored less time amounts now to 0 seconds.

In a seventh and last cleaning process according to the illustration, the timer is set to the standard duration of 120 seconds, since in the cleaning time account, no miss-out times are stored. This time, no warning signal sounds upon switching on of the tooth brush. The user cleans until the timer signal, which is emitted after 120 seconds and than for another 30 seconds until to a total cleaning time of 150 seconds. In the shown embodiment, the actual cleaning times over the target cleaning time are not assessed, that is, the cleaning time account is set upon reaching the target cleaning time merely to 0. This was provided in the present case, so that the value of the cleaning time account MPK remains at 0 seconds. 

1. A method of operating a toothbrush to specify a target length of time for cleaning teeth, the method comprising: measuring an actual cleaning time during a first cleaning process using a time determination device of the toothbrush, a duration of the first cleaning process including a duration of a temporary interruption of the cleaning process that is less than a predetermined maximum interruption time limit; determining a deviation of the actual cleaning time from a standard cleaning time using an evaluation device of the toothbrush; and determining a target cleaning time for a subsequent cleaning process as a function of the determined deviation and the standard cleaning time using a control device of the toothbrush, wherein the target cleaning time is a summation of the standard cleaning time and the determined deviation.
 2. The method according to claim 1, further comprising, during the subsequent cleaning process, indicating to a user a termination of the target cleaning time.
 3. The method according to claim 1, wherein the determined deviation is stored in a memory.
 4. The method according to claim 1, wherein the deviation is limited to a predetermined deviation limit.
 5. The method according to claim 4, wherein the predetermined deviation limit is about 90 seconds.
 6. The method according to claim 1, wherein the standard cleaning time is about 120 seconds.
 7. The method according to claim 1, wherein the target cleaning time is adjusted to fall within a predetermined span of acceptable cleaning time.
 8. The method according to claim 7, wherein the target cleaning time is limited to be greater than or equal to the standard cleaning time.
 9. The method according to claim 1, wherein, in response to the actual cleaning time being greater than the standard cleaning time, the target cleaning time is less than the standard cleaning time.
 10. The method according to claim 1, wherein, if the target cleaning time differs from the standard cleaning time, at the beginning of a subsequent tooth cleaning, a non-standard warning signal is emitted.
 11. The method according to claim 1, wherein a sub-minimum warning signal is emitted if the actual cleaning time is determined to be less than the predetermined minimum cleaning time limit.
 12. The method according to claim 1, wherein a sub-target warning signal is emitted if an actual cleaning time of the subsequent cleaning process is determined to be less than the target cleaning time.
 13. The method according to claim 1, wherein the actual cleaning time is determined as a time interval between an operator activating and deactivating a tooth cleaning device.
 14. The method according to claim 13, wherein, the actual cleaning time continues to be measured upon temporary interruption of operation of the tooth cleaning device if the interruption is less than a predetermined maximum interruption time limit.
 15. A method of operating a toothbrush to specify a target length of time for cleaning teeth the method comprising: measuring an actual cleaning time during a first cleaning process using a time determination device of the toothbrush, a duration of the first cleaning process including a duration of a temporary interruption of the cleaning process that is less than a predetermined maximum interruption time limit; determining a deviation of the actual cleaning time from a standard cleaning time using an evaluation device of the toothbrush; and determining a target cleaning time for a subsequent cleaning process as a function of the determined deviation and the standard cleaning time using a control device of the toothbrush, wherein the deviation between the actual cleaning time and the standard cleaning time is only determined when the actual cleaning time of a tooth cleaning lies above a predetermined minimum cleaning time.
 16. The method according to claim 15, wherein the predetermined minimum cleaning time is about 30 seconds.
 17. A method of operating a toothbrush to specify a target length of time for cleaning teeth, the method comprising: measuring an actual cleaning time during a first cleaning process using a time determination device of the toothbrush, a duration of the first cleaning process including a duration of a temporary interruption of the cleaning process that is less than a predetermined maximum interruption time limit; determining a deviation of the actual cleaning time from a standard cleaning time using an evaluation device of the toothbrush; determining a target cleaning time for a subsequent cleaning process as a function of the determined deviation and the standard cleaning time using a control device of the toothbrush; and storing multiple deviations corresponding to multiple tooth cleanings and determining the target cleaning time of a subsequent tooth cleaning as a function of a sum of the multiple deviations.
 18. The method according to claim 17, wherein the sum of deviations is limited to a predetermined limit.
 19. The method according to claim 18, wherein the predetermined limit is 90 seconds.
 20. An electric tooth cleaning device, comprising: a tooth cleaning element; a motor; a motor controller that controls the motor and is configured to measure an actual cleaning time during a first cleaning process, where a duration of the first cleaning process includes a duration of a temporary interruption of the cleaning process that is less than a predetermined maximum interruption time limit; determine a deviation of the actual cleaning time from a standard cleaning time; and determine a target cleaning time for a subsequent cleaning process as a function of the determined deviation and the standard cleaning time, wherein the target cleaning time is a summation of the standard cleaning time and the deviation.
 21. The electric tooth cleaning device of claim 20, further comprising an indicator that indicates a termination of the target cleaning during a subsequent cleaning.
 22. The electric tooth cleaning device of claim 21, wherein the indicator is an acoustic device.
 23. The electric tooth cleaning device of claim 21, wherein the indicator is an optical device.
 24. The electric tooth cleaning device of claim 20, wherein the controller limits the deviation to a predetermined deviation limit.
 25. The electric tooth cleaning device of claim 24, wherein the predetermined deviation limit is about 90 seconds.
 26. The electric tooth cleaning device of claim 20, wherein the standard tooth cleaning time is about 120 seconds.
 27. The electric tooth cleaning device of claim 20, wherein the controller includes a memory in which the target cleaning time is stored.
 28. The electric tooth cleaning device of claim 20, wherein the controller adjusts the target time to fall within a predetermined span of acceptable cleaning times.
 29. The electric tooth cleaning device of claim 28 wherein the target cleaning time is limited to be greater than or equal to the standard cleaning time.
 30. The electric tooth cleaning device of claim 20, wherein, in response to the actual cleaning time being greater than the standard cleaning, the target cleaning time is less than the standard cleaning time.
 31. The tooth cleaning device of claim 20, wherein the controller is configured to initiate a sub-target warning signal upon termination of the actual cleaning time in response to measuring an actual cleaning time less than the target cleaning time.
 32. The tooth cleaning device of claim 20, wherein the controller is configured to initiate a sub-minimum warning signal in response to measuring an actual cleaning time less than a predetermined minimum cleaning time.
 33. The tooth cleaning device of claim 20, wherein, as a subsequent cleaning is commenced, the controller initiates a non-standard warning signal that the target time differs from the standard time.
 34. The electric tooth cleaning device of claim 20, wherein the actual cleaning time is determined as a time interval between an operator activating and deactivating the cleaning device.
 35. The electric tooth cleaning device of claim 34, wherein the controller is configured to continue measuring actual cleaning time during a temporary interruption of operation of the cleaning device if the interruption is less than a predetermined minimum interruption time limit.
 36. An electric tooth cleaning device, comprising: a tooth cleaning element; a motor; a motor controller that controls the motor and is configured to measure an actual cleaning time during a first cleaning process, where a duration of the first cleaning process includes a duration of a temporary interruption of the cleaning process that is less than a predetermined maximum interruption time limit; determine a deviation of the actual cleaning time from a standard cleaning time; and determine a target cleaning time for a subsequent cleaning process as a function of the determined deviation and the standard cleaning time, wherein the controller determines a deviation only when the actual cleaning time is above a predetermined minimum cleaning time limit.
 37. The electric tooth cleaning device of claim 36, wherein the predetermined minimum cleaning time limit is about 30 seconds.
 38. An electric tooth cleaning device, comprising: a tooth cleaning element; a motor; a motor controller that controls the motor and is configured to measure an actual cleaning time during a first cleaning process, where a duration of the first cleaning process includes a duration of a temporary interruption of the cleaning process that is less than a predetermined maximum interruption time limit; determine a deviation of the actual cleaning time from a standard cleaning time; and determine a target cleaning time for a subsequent cleaning process as a function of the determined deviation and the standard cleaning time, wherein the controller is configured to store multiple deviations corresponding to multiple tooth cleanings, and to determine the target cleaning time as a function of a sum of the deviations.
 39. The electric tooth cleaning device of claim 38, wherein the controller limits the sum of deviations to a predetermined limit.
 40. The electric tooth cleaning device of claim 39, wherein the predetermined limit is 90 seconds. 